US3814877A

US3814877A - Pressure switch with diaphragm and adjustable contact

Info

Publication number: US3814877A
Application number: US00298368A
Authority: US
Inventors: W Alvarez
Original assignee: Jonathan Manufacturing Co
Current assignee: Jonathan Manufacturing Co
Priority date: 1972-10-17
Filing date: 1972-10-17
Publication date: 1974-06-04
Anticipated expiration: 1991-06-04

Abstract

A flexible polymeric-metal laminate diaphragm is used in a pressure responsive switch for engaging and disengaging switch terminals in accordance with periodic changes in pressure.

Description

I United States Patent [1 1 7/1960 Dodge Alvarez [451 June, 4, 1974 PRESSURE SWITCH WITH DIAPHRAGM 3,594,522 7/1971 Colglazier 200/83 N x AND ADJUSTABLE CONTACT 3,689,719 9/1972 Phillips et al. 200/83 X [75] Inventor: WiIliam Alvarez, Placentia, Calif. FOREIGN PATENTS OR APPLICATIONS Assignee: Jonathan Manufacturing p y, l,0l3,778 8/1952 France 200/83 N Fullerton, Calif. I OTHER PUBLICATIONS [22] Filed: Oct. 17, 1972 IBM Technical Disclosure, Pressure Sensitive Elastic v Diaphragm Switch"; Vol. 14, No. 3, p. 878; 8/1971;

[2]] Appl DeBeaumont et al. I

[52] US. Cl. 200/83 N, 200/8l.9 R 7 Primary Examiner-Robert K. Schaefer [5]] Int. Cl. 01h 35/34 Assistant Eraminer--Gerald P. Tolin [58] Field of Search......... 200/83-N, 8-1.9 R, 159 B, r

. 2.00/86 A 57 ABSTRACT UNITED STATES PATENTS gaging switch terminals in accordance with periodic 1,998.82! 4/1935 Rockwell 200/83 N ux Changes in pressure 2,768,26l 10/1956 Mathisen I 200/83 N 2,944,558 ZOO/81.9 RX '1 Claim, 2 Drawing Figures a PRESSURE swircii'wiru DIAPHRAGM AND ADJUSTABLE CONTACT BACKGROUND OF INVENTION being those in which a flexible diaphragm is exposed to fluid pressure to be sensed which, if excessive, deflects the diaphragm which, in turn, activates suitable mechanism arranged to close or open an electric circuit, as the case may be. Various types of diaphragms are used such as for example, single or double thin sheet metal discs of the snap-action type as disclosed in U.S. ,Pat. No. 3,585,3 28; diaphragms of the type requiring reset structure as shown in U.S. Pat. No. 3,579,284, and U.S. Pat. No. 3,29 I932; orspring-Ioaded diaphragms of the type disclosed in U.S. Pat. No. 3,600,535. Moreover, in substantially every instance, the diaphragms are designed either to carry or activate auxiliary members for energizing an electric circuit. Thus these and similar diaphragm-type switches of the prior art-embody a mul- 'tiplicity of components including many moving parts,

some of which'are of relatively heavy construction. As

a consequence, these switches are relatively slow acting and relatively insensitive to slightchanges in pressure.

It is desirable, however, for certain applications such as, for example, on-off switches, unit counters and the like, to provide a pressure responsive switch which is sensitive to minimal pressure differentials and is ex- The present invention achieves these objectives by phragm to establish relative negative pressure or vacuum, as the case may be, which deflects the diaphragm in the reverse direction thereby disengaging its coppersurfaced side from contact with the switch terminal means.

In the normally off switch illustrated herein, the diaphragm is mounted in a chamber within a dielectric body member having air passages arranged to conduct air to the dielectric side of the diaphragm and from thence to the atmosphere. The copper surfaced side of the diaphragm or current-conducting side as it is sometimes hereinafter called, is arranged opposite and spaced from one or more switch terminal means providing a pressure responsive switch having no moving parts other than the flexible'diaphragm itself which is characterized by extremely light weight construction and hence is not only sensitive to very smallchanges in pressure, as for example, a pressure differential of as low as l/4 inch water, but substantially immediately responsive thereto to effect energization of electric circuitry. More particularly, the pressure responsive electric switch of this, invention is characterized by'the use of a thin flexible diaphragm approximately 0.0025 inches thick comprising a polymeric-metal laminate and in particular a dielectric plastic sheet surfaced on one side with a metalsuch as copper and mounted in the switch assembly in a manner to permitthe diaphragm to flex freely and in so doing deflect its coppersurfaced side into and from contact with suitable switch terminal means in response to variations in pressure acting on the diaphragm. These variations in pressure are effected by a fluid and in particular by a stream of air which normally flows past the diaphragm and in so doing subjects it either to minimal positive pressure or negative pressure. as the case may be.

Assuming the switch is designed to be normally off, as hereinafter described, to activate the switch to its on" position, the flow of air past the diaphragm is momentarily restricted or stopped, as the case may be, whereupon the pressure of air against the diaphragm is increased sufficiently to deflect the coppersurfaced side of the diaphragm into contact with the switch terminal means. Upon releasing the air the pres sure on the diaphragm is lowered sufficiently at the diamounted in the body member. A source of air is connected to the air passages and arranged normally to provide a steady flow of air through the passages from which the air exits to the atmosphere. The switch is made to function as an on-off" switch or as a unit counting device by successively closing and opening theair exit passage to the atmosphere-and due to the relative simplicity of construction .and the light weight of the diaphragm, the latter may be made to respond with great rapidity to the closing and opening of the exit passage.

While the embodiment of the invention shown herein and hereinafter described comprises a switch assembly adapted to be normally off and to be turned on periodically it will be understood that the invention is designed to operate in reverse to be normally on and to be turned off periodically.

DESCRIPTION OF DRAWINGS PREFERRED EMBODIMENT OF THE INVENTION Referring to FIG. 1, the pressure responsive switch assembly will be seen to comprise a body member indicated generally at 10. The latter may take the shape of a substantially rectangular or disc-shaped block formed of a dielectric material such as a polymeric plastic or the equivalent, and is fashioned from two separate but complimentary parts, indicated at 11 and l2respectively secured together at a common interface 13 by suitable fastening means such as machine screws as il- .Iustrated at 14.

The inner surface of the part 11 at interface 13 is provided with a relatively shallow recess 15 dimensioned to accomodate a major portion of the flexible diaphragm hereinafter described. Part 11 is also provided with an internally threaded aperture 16 which extends inwardly from the outer face of part II on an axis substantially coincident with the center of the recess 15 the diameter of the aperture 16 being such as to accommodate an externally threaded stud screw 17 which serves as a switch terminal. To this end, the latter is threaded into the aperture 16 sufflciently that the inner end of the stud screw 17 extends a short distance into the recess 15; and is provided with a lock nut 18 by which the inner endof the stud screw may be fixedly secured in a selected adjusted position in the recess 15.

A second switch terminal is provided in part 11 and, as indicated at 19, may take the form of 'a machine screw threaded into an aperture adjacent to the outer edge of the part 11 and arranged to extend therethrough to the interface 13. The machine screw 19 is also provided with a lock nut as at 20 for locking the screw in adjusted position. Both the

switch terminal

17 and 19 are provided with wire leads 21- 21 adapted to be connected to electric circuitry including a source of electric energy, and auxiliary motor driven equipment (not shown).

I The block 12, which is adapted to be secured to tively, each of relatively small diameter. The passage 22 extends entirely through part 12 from its inner face, as defined by interface 13, to its outer or bottom face, as seen in FIG. 1, its longitudinal axis being substantially in allignment with the longitudinal axis of the stud screw 17. Passage or gallery 23 is drilled or otherwise formed in part 12 substantially intermediate its inner face and. its bottom face and at substantially right angles to passage 22. The inner end of passage 23 intersects passage 22 while its outer end is enlarged by an internally threaded counterbore 24 formed in the corresponding side wall of part 12. The counterbore 24 is adaptedto receive fitting 25 by which an air hose 26 is connected to passage 23. i

Mounted between the two parts 11 and 12 of the dielectric block at the interface 13 thereof is a flexible diaphragm 27. The latter comprises a thin sheet of dielectric material, one side of which is surfaced with a current conducting metal such as copper. A particularly satisfactory diaphragm is a flexible polyimidemetal laminate, comprising a thin sheet of a dielectric polymid polymer coated on one side with copper. Typical laminates are those used as electric .circuit boards and the like as disclosed in US. Pat. Nos. 3,179,614 and 3,582,458.

In the embodiment of FIG. 1, diaphragm 27 is dimensioned to span the recess .15 and is sandwiched securely between the inner faces of the upper and lower parts 11 and 12 respectively of the dielectric block 10 with a fluid tight joint. When so assembled, the recess constitutes a diaphragm chamber. The copper surface of the diaphragm is disposed uppermost so as to be opposite the inner end of the terminal stud screw 17 but spaced therefrom; and for permanentengagement by the inner end of the terminalscrew 19.

t The operation of the pressure responsive switch of FIG. 1 is as follows: a gas, such as air, is continuously supplied to the passage 23, via air pipe 26 and fitting 25, at relatively low pressure, as for example, 2.5 inches water. The air passes through the passage 23 and passage 22 and escapes to the atmosphere via of air exit orifice 28. Since the diameters of the passages and orifice are relatively small, slight back pressure is created within the passage 22, which causes the diaphragm to partially deflect toward the inner end of the terminal stud screw 17 but insufficiently to contact it the space therebetween being of the order of a few thousandths inches. Upon closing air exit orifice 28, the back pressure in passage 22 is increased thereby defleeting the diaphragm into contact with the terminal stud screw 17 and providing electrical continuity be tween stud screw 17 and terminal screw 19 via of the copper surface of the diaphragm. As soon as air exit orifice 28 is uncovered, the back pressure is reduced and the partial vacuum created by the venturi effect at the intersection of the

passages

22 and 23 returns the diaphragm to its original position thus opening the electric path between

terminals

17 and 19.

Because of its simplicity of construction and the light weight of the diaphragm, the latter has been found to respond at a rate in the range from O to 45 pulsations/- sec. to alternate closing and opening of the air exit orifice 28 and hence the assembly is extremely useful as a rapidly acting onofF switch.

Referring to the modification shown in FIG. 2 wherein elements similar to those of FIG. 1 are similarly identified, the pressure responsive switch is designed specifically as a unit counter. This switch assembly, indicated generally at 30, is preferably rectangular in cross-section and comprises two

parts

31 and 32, each formed of a suitable dielectric material and secured together by fastening means such as machine screws or the like as indicated at 33. The part 31 is provided on its inner face with a shallow rectangular or circular recess 34. At the center of the recess 34 a small aperture 35 is drilled through the reduced section of the part 31 to the outer face thereof. Additional apertures are drilled through the reduced section of part 31 on opposite sides respectively of the central aperture 35 to accommodate round headed machine screws 36 36 the heads of which are located in the recess 34.

Adjusting nuts 37 37 and lock nuts 38 38 are threaded on the outer extremities of the machine screws for securing the latter in predetermined adjuste'd positions and for attaching wire leads 39 39 thereto.

The machine screws 36 36 thus serve as switch terminals of electric circuitry connected to the wire leads 39 39.

The part 32 of the dielectric block 30 comprises a substantially rectangular body portion, the bottom of which is characterized by integral forwardly and rearwardly extending shoes 40 40, the soles of which form a continuous substantially smooth surface 41 for engagement by unit articles to be counted.

Referring to the upper portion of part 32, its face, 0pposite that of the recessed part 31, is provided with a recess 42 somewhat deeper than the recess 34 in part 31 but dimensioned to compliment the latter so that when the

parts

31 and 32 are secured together, the

recesses

34 and 42 form a single chamber for accomodating the flexible diaphragm 27. As in the assembly of FIG. 1, the diaphragm is dimensioned to span the chamber and is held securely therein by being sandwiched between the two

parts

31 and 32 the latter being securely held together with a fluid tight joint by machine screws 33.

A passage or gallery 43, of relatively small diameter, is drilled substantially vertically, as seen in FIG. 2 through part 32 from top to bottom. Its upper end is enlarged by an internally threaded counterbore 24 for attaching a fitting 25 and air hose 26 thereto, while the lower end of the passage 43 forms an air exit orifice 44 in the sole 41 of said shoes.

A second passage identified at 45, also of relatively small diameter, is formed in part 32 substantially at right angles to passage 43 and connects the latter to the recess 42 substantially centrally thereof.

The operation of the switch assembly of FIG. 2 is as follows: A gas, such as air, under positive pressure of the order of from 2.5 to 5 lbs/square inch is introduced continuously to passage 43. As long as air exit orifice 44 is open, the gas flows past passage 45 to the atmosphere and in so doing, creates a venturi effect, i.e., negative pressure in passage 45, which, in conjunction with the atmospheric pressure acting on the opposite side of diaphragm 27 (because of aperture 35) holds the current conductive side of diaphragm away from the terminal contacts 36 36. However, as soon as the air exit orifice 44 is closed pressurized air enters passage 45 and creates positive pressure on the corre- .sponding side of the diaphragm, which pressure exceeds the atmospheric pressure on the current conducting side thereof. As a consequence, the flexible diaphragm is deflected to engage its current conducting side with the switch terminals, as indicated by the dotted lines, to provide electrical continuity from one to the other via the copper surface of the diaphragm.

In the embodiment shown herein, the air exit orifice 44 is adapted to be successively opened and closed by unit articles, indicated at 46,'fed' forwardly continuously against the shoe 4] of the assembly past the orifice 44.Thus as each article approaches and closes the orifice 44, the diaphragm is flexed into contact with the switch terminals thereby energizing the switch assembly; and as the articles pass beyond the orifice 44, the diaphragm is withdrawn from contact with the switch terminals and the switch is deenergized. The alternate energizing and deenergizing of the switch assembly may operate electric circuitry including counting means whereby the articles may be continuously counted.

in the embodiment of the invention shown in each of H68. 1 and 2 the switches are designed as normally of that is to say the current conducting side of the flexible diaphragm is normally out of contact with the switch terminal means and is moved into contact by applying air pressure to the opposite side of the diaphragm, It would be understood, however, that either one of the switches of FIGS. 1 and 2 may be modified in a manner to be normally on by the obvious and relatively simple expedient of adjusting the switch terminal means normally to engage the current conduct- 6 ing side of the diaphragm and introducing the pressurized air against the same side of the diaphragm to move its current conducting side away from the switch terminal means thereby opening the switch which modifications are contemplated within the scope of the present invention.

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments, are therefore, to be considered in all respects as illustrations and not restrictive and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

l claim:

1. A pressure responsive electric switch assembly comprising a dielectric body member, a chamber in said body member, adjustable switch terminal means comprising a metal terminal post threadedly engaged in said dielectric body member with one end extending into said chamber, a thin flexible diaphragm arranged in said chamber said diaphragm comprising a dielectric polymer approximately 0.0025 inches thick and surfaced on the side opposite said adjustable switch terminal means with a coating of metal for contact therewith, and two air passages in said body member, one air passage opening at one end into said chamber and the opposite end of said one air passage having an unrestricted opening directly exposed to the atmosphere, the 2nd air passage intersecting said one air passage,

' said Znd air passage being connected at one end to a continuous source of pressurized air and at the other end closed at a point beyond the intersection of the passages, the said one air passage exposing one side of said flexible diaphragm intermittently to positive and negative air pressure in accordance with the non-flow and flow respectively of air'from said unrestricted opening to the atmosphere whereby the metal surfaced side of said diaphragm is selectively moved into and from electrical contact with said adjustable switch terminalmeans.

Claims

1. A pressure responsive electric switch assembly comprising a dielectric body member, a chamber in said body member, adjustable switch terminal means comprising a metal terminal post threadedly engaged in said dielectric body member with one end extending into said chamber, a thin flexible diaphragm arranged in said chamber said diaphragm comprising a dielectric polymer approximately 0.0025 inches thick and surfaced on the side opposite said adjustable switch terminal means with a coating of metal for contact therewith, and two air passages in said body member, one air passage opening at one end into said chamber and the opposite end of said one air passage having an unrestricted opening directly exposed to the atmosphere, the 2nd air passage intersecting said one air passage, said 2nd air passage being connected at one end to a continuous source of pressurized air and at the other end closed at a point beyond the intersection of the passages, the said one air passage exposing one side of said flexible diaphragm intermittently to positive and negative air pressure in accordance with the non-flow and flow respectively of air from said unrestricted opening to the atmosphere whereby the metal surfaced side of said diaphragm is selectively moved into and from electrical contact with said adjustable switch terminal means.